Paints which have to be hardened in an inert-gas atmosphere, for example under UV light, in order to prevent unwanted reactions with constituents of the normal atmosphere, in particular with oxygen, have increasingly gained importance recently. These new types of paint are distinguished by very great surface hardness and very short polymerisation times. In the case of painting installations which are operated with the articles running through continuously, the last-mentioned advantage translates directly into shorter installation lengths, which naturally leads to considerably lower investment costs.
In order to reduce the consumption of inert gas and in this way save on costs, it is known, from DE 10 2004 025 528 A1, to take inert gas from the drying tunnel constantly or intermittently. This gas is then conducted along a face which is cooled down to a temperature that lies below the dew point of the lowest-boiling contaminants contained in the inert gas. In this way, substantially all the contaminants condense out on this cooled face.
This known installation and process, which work at a single condensation temperature, are not yet optimum energy-wise or as regards cleaning efficiency.